This invention generally relates to visual videoprobe equipment. In particular, this invention relates to a miniaturized videoprobe and videoprobe apparatus that is insertable into small spaces where previously, only fiberscope equipment was insertable.
Up to now, inspections of small restricted spaces and areas have been accomplished with flexible fiberscopes. The fiberscope technology relies on transmitting light through approximately 15 feet of a fiber-optic light guide, illuminating an object at the end of the fiberscope, receiving the light reflected back from the object, and transmitting the image back through the approximately 15 feet of fiber-optics to a charge couple device (CCD) chip located in a video camera. Such fiberscope arrangements have the disadvantage that information is lost during transmission of the reflected image back to the CCD chip in the camera body, thereby reducing the quality of the pictorial information received by the CCD chip.
Videoprobes also are common place in the prior art. Due to their size and configuration, prior art videoprobes have been unable to enter the same small, restricted spaces as fiberscopes. The prior art videoprobes typically have a circular cross-section with the CCD and accompanying circuitry on the front face. The smallest commercially available videoprobe is approximately 0.25xe2x80x3 in cross-section. Videoprobes miniaturized to 0.110xe2x80x3 requirements become overly fragile and easily damaged.
However, videoprobes still have a distinct advantage over fiberscopes by their placement of the CCD at the end of the device, adjacent the object being viewed. The CCD chip in the videoprobes then provides an electrical signal output representing the viewed image. This signal is transmitted back to a signal processor, which is approximately 15 feet removed from the CCD chip. The signal processor provides an NTSC TV signal. The overall arrangement in a videoprobe significantly reduces image transmission losses and allows use of an improved optic lens train which results in an improved field of view, focal ranges, depth of view, and image resolution.
The present invention overcomes image loss characteristics of fiberscopes by providing a miniaturized videoprobe, and videoprobe apparatus. The present invention overcomes fragility in, and strengthens a miniaturized videoprobe by incorporating a noncircular, circular, generally rectangular cross-section which differs from the generally circular shape of prior art videoprobe assemblies. The present invention places the CCD and accompanying circuity along a linear axis perpendicular to a front face of the videoprobe. The present invention is able to enter spaces as small as 0.125xe2x80x3 that up to now were not accessible by prior art videoprobes.
A preferred embodiment of the present invention is a miniature videoprobe apparatus comprised of a Lexan (a registered trademark of General Electric Co.) plastic delivery tool strong back fabricated in the general shape of a hockey stick. The end of the hockey stick structure has a termination box with an umbilical connection to a videoprobe light supply and image signal processor. The other end of the hockey stick houses videoprobe electrical components and an optics train sandwiched between two thin stainless steel machined pieces. Within the hockey stick encasement, milled channels down the length of the stick pass fiber-optic light guides and image signal output wiring from the CCD chip electronics package. A preferred embodiment also has two additional utility or auxiliary channels to allow material sampling and nitrogen drying of areas of interest investigated by the videoprobe. The utility channels provide means for insertion of a fiberscope to provide a second image in addition to the one from the CCD chip.
The key advantages of this invention are related to the improved images now available from areas previously accessible only to fiberscopes. The image quality is significantly better, automatic focus eliminates manual focusing, the field depth is much improved, and the field of view is larger with the focal range being longer. The videoprobe is carried within the delivery tool to ensure that the orientation of the picture on the monitor is known as compared to a circular fiberscope whose alignment needs to be verified and frequently reoriented.
The present invention has possible application in jet engine visual exams, boiler tube inspections, medical invasive procedures, and checking the internal passages of complicated machine part castings. There is also potential for use by other U.S. Government projects that have inspection requirements for small internal areas requiring high quality resolution.